There are a variety of different types of situations in which it is desirable to control a blood flow for therapeutic or surgical reasons. In some cases, it is important to slow or stop the flow of blood in a patient, while in other instances, it is desirable to increase the flow of blood to a particular part of a patient's anatomy.
One example is to stem bleeding. Bleeding is an unavoidable and ever-present consideration in any medical condition or intervention that involves a skin incision (or skin laceration) or procedure directed to deeper/internal organ structures. It is particularly important when performing surgery. This can be especially critical in those cases where the procedure or medical situation has potential to lead to unexpected hemorrhaging. Bleeding, whether minor or major, always presents several challenges.
Undesirable flow of blood in the operative site or operative field must be managed to preserve unobstructed view of anatomic structures to be incised or repaired to avoid surgical errors. This typically necessitates the involvement of an assistant, who will sponge or suction the blood as it accumulates and obscures the local anatomy. This requires an additional set of hands in the operative site, which both results in crowding of the area in which the surgeon needs to work and increases the risk of infection and accidental injury.
Additionally, some medical practitioners have used drapes that contain a pouch to collect the blood (as well as other fluids). For example, during abdominal surgery, a fluid collection pouch may be placed adjacent one side of the surgical site and extending down the side of the patient, while in arthroscopy surgery, the patient's leg may be placed through a collection pouch mounted to a drape, with one sheet of the collection pouch in front of the surgical site on the limb and another sheet of the collection pouch in back of the surgical site, such that the fluid collection pouch is supported in part by the limb itself and in part by the surgical drape (to which the fluid collection pouch is attached). Some drapes include fluid collection pouches with a port for connecting a suction hose to help facilitate removal of the fluid. However, collection pouches pose numerous difficulties, including that the positioning of the pouch can make it difficult to adequately expose the surgical site, that it may not provide an optimal opening for capturing the blood, and that it may leak.
More importantly, intraoperative attempts to stem or stop the blood flow, and the need to arrest post-operative bleeding, have traditionally required the use of additional instruments and/or agents. In particular, pneumatic tourniquets are often employed for this purpose. This consists of using an inflatable cuff to provide tissue compression to occlude the blood flow. The use of such devices suffers from a number of disadvantages.
First, the use of a pneumatic tourniquet to stop intraoperative bleeding is not always effective. Often, bleeding will still occur due to an under-pressurized cuff, insufficient exsanguination, improper cuff selection, a loosely applied cuff, calcified blood vessels resistant to the cuff, or insufficiently quick inflation/deflation.
Additionally, the use of traditional tourniquets to control bleeding at the surgical site has been shown to increase morbidity. A common problem is nerve injury, which appears to be attributable to both mechanical compression and neural ischemia, and which can result in mild transient loss of function to irreversible damage and paralysis. Other potential complications from the use of traditional tourniquets are compartment syndrome, pressure sores, chemical burns, digital necrosis, deep venous thrombosis leading to pulmonary or venous embolization, pain, thermal damage to tissues, and rhabdomyolysis. A common post-operative complication from use of pneumatic tourniquets is hematoma or hemarthrosis formation, from the tourniquet pressure during surgery being too low and allowing arterial blood pressure to push blood from the arterial system past the tourniquet into the extremity while the tourniquet provides enough pressure to prevent the venous blood flow system from returning the blood. The venous blood ends up pooling in the operative site, compromising the surgical field of view, or in the surrounding tissues resulting in a postoperative hematoma, with its many associated complications and difficulties. Similarly, when the tourniquet is deflated after the procedure there is an immediate post-operative reactive hyperemia or vasodilatation, which predisposes one to bleeding in the operative site after the wound is closed.
Further, in difficult cases, a pneumatic tourniquet is not sufficient to adequately slow blood flow. In these cases, in order to sufficiently control bleeding at the surgical site, it is necessary to withdraw the surgical instrument and insert an electrocautery probe through the same opening. To utilize electrocautery, the body of the patient is grounded, and the tip of the energized electrocautery probe is pressed against the tissue from which the blood is flowing. A high frequency electrical current flows from the probe through the tissue of the patient, and the tissue, including any open blood vessels therein, is heated by the current, coagulating the tissue and sealing the open ends of the blood vessels. The blood produced prior to this must then be removed from the surgical site using a flow of sterile fluid (irrigation) to restore visibility in the surgical site, and then the surgical tool is reinserted to resume the surgery.
This removal of the surgical instrument when bleeding occurs, the subsequent insertion of the electrocautery probe, the removal of the probe after cauterization, and the reinsertion of the surgical instrument thereafter is a difficult, time-consuming task that only further increases risk of injury or infection. Moreover, during the time between the removal of the surgical instrument and the insertion of the electrocautery probe, a significant amount of blood can accumulate at the surgical site, making it difficult to visually locate the actual source of the bleeding. Even if one were able to use a single surgical instrument that was also able to act as an electrocautery probe, the cauterization process inflicts undesirable trauma to the relevant tissue.
Efforts to control bleeding often also include the use of pharmaceutical agents. For example, in the past, it was customary to take a unit of the patient's own blood three weeks before the surgery (to allow the body to replenish), which would then be an extra unit of blood to be used during the surgical and post-operative periods, as a method to avoid the complications of HIV and Hepatitis from regular typed and crossed transfusions from the general blood bank. However, this approach still had problems, as it often resulted in a lower starting blood count (patients didn't regenerate to normal levels before the surgery in a three-week time frame). It also did nothing to control the actual problem of bleeding. Currently, transfusions, and the complications associated with them, are rarer because of the use of tranexamic acid, which is sometimes administered (both before and after surgery) to slow the breakdown of blood clots, and thereby prevent blood loss, thus reducing the need for blood transfusions. The side effects of tranexamic acid in the postoperative period can include nausea, constipation, and sensitivity reactions and, although not definitively proven, could potentially be associated with abnormal increased clotting that although it may stop the blood flow, could result in DVT (deep vein thrombosis) and/or pulmonary embolism.
Additionally, pharmacological agents such as bupivacaine and other local anesthetics are sometimes administered preoperatively (as in nerve blocks for regional anesthesia) or to treat post-operative and recovery pain. To help extend the time that these agents are effective, they are often combined with epinephrine. Epinephrine causes vasoconstriction so that the body takes longer to remove the local anesthetic from the area being treated. However, epinephrine has multiple other actions, such as causing tachycardia or elevated blood pressure, that are detrimental to recovery and can cause serious intraoperative and postoperative complications. Such use of epinephrine in this manner needs to be monitored (vital signs) to be sure complications are not occurring. Because these agents or combinations of them can have undesirable side effects, it is preferable to employ a method of controlling intraoperative and post-operative bleeding that does not rely on them.
In other cases, it is desirable to increase (rather than decrease) blood flood to a particular area. For example, after a surgery has been completed and the relevant anatomy sutured back together, it may at some point become beneficial to increase blood flow to the affected area in order to promote healing.
There are various other scenarios in which an increase in blood flow to a specific part of a patient's anatomy can achieve beneficial therapeutic effects. For example, it may be desirable to increase the flow of blood to a patient's foot when treating peripheral vascular disease or after the debridement of diabetic foot ulcers.
Therefore, what is desired is a system and method for controlling blood flow at a surgical site or other wound that does not require having to clear and remove large, or small but strategically localized, amounts of blood exuded by the incision or wound. What is also desired is a system and method for preventing blood loss that does not require the use of excessive pressure that causes trauma to the body. What is further desired is a system and method for preventing blood loss that does not require the use of additional devices that cause other trauma to the body. What is also desired is a system and method for preventing blood loss that does not depend upon the administration of pharmaceuticals. What is further desired is a system and method for controlling blood flow that can increase blood flow to a part of the anatomy, if needed.